A variety of gas sterilization methods has been investigated in the past. Methods using ethylene oxide and other disinfecting gases are widely used for sterilizing a wide range of medical products from pharmaceutical preparations to surgical instruments. Irradiation alone and together with disinfecting gases has also been investigated, as summarized by Russell, A.; The Destruction of Bacterial Spores.; New York: Academic Press (1982).
A sterilizing method must effectively kill all organisms, including spores, without damage to the article or goods being sterilized. However, many disinfecting methods which meet this criteria, such as ethylene oxide and irradiation methods, have been found to expose workers and the environment to unacceptable safety hazards. States and Federal legislation are severely restricting the amount of hazardous gases such as ethylene oxide (a carcinogen) in the working environment, or the use of any system or method which produces toxic residues or exhaust products. This is presenting a major crisis in hospitals and other areas of the health industry.
The use of plasma to sterilize containers was suggested in U.S. Pat. No. 3,383,163. Plasma is an ionized body of gas which may be generated by the application of power from different sources. The ionized gas will contact microorganisms on the surfaces of the items to be sterilized and effectively destroy the microorganisms.
Sterilizing plasmas have been generated with a wide variety of gases: argon, helium or xenon (U.S. Pat. No. 3,851,436); argon, nitrogen, oxygen, helium or xenon (U.S. Pat. No. 3,948,601); glutaraldehyde (U.S. Pat. No. 4,207,286); oxygen (U.S. Pat. No. 4,321,232); oxygen, nitrogen, helium, argon or freon with pulsed pressure (U.S. Pat. No. 4,348,357); hydrogen peroxide (U.S. Pat. No. 4,643,876); nitrous oxide, alone or mixed with oxygen, helium or argon (Japanese Application Disclosure No. 103460-1983); and nitrous oxide, alone or mixed with ozone (Japanese Application No. 162276-1983). Unfortunately, these plasma methods have proven to be too corrosive to articles being sterilized, and particular packaging materials; have left toxic residues on the sterilized articles; or have presented other safety or environmental hazards.
Non-plasma gas sterilization procedures have been described using ozone (U.S. Pat. No. 3,704,096) and hydrogen peroxide (U.S. Pat. Nos. 4,169,123; 4,169,124; 4,230,663; 4,366,125; 4,289,728; 4,437,567; and 4,643,876). These materials are toxic and leave undesirable residues.